/Engine/Source/Editor/MeshPaint/Public/MeshPaintHelpers.h
Retrieves the number of bytes used to store the per-instance LOD vertex color data from the static mesh component
static void GetInstanceColorDataInfo ( const [UStaticMeshComponent](API\Runtime\Engine\Components\UStaticMeshComponent) * StaticMeshComponent, int32 LODIndex, int32 & OutTotalInstanceVertexColorBytes )